The present invention relates to an adjustment assembly for head positioning means in a cephalostat used for positioning the head while taking radiographs, particuarly in cephalometric study. The invention has particular suitability for those cephalostat devices used to obtain tomograms of the dentition. The adjustment assembly provides a very close, exact and stable adjustment capability while importantly eliminating support arms and rods from projecting outwardly of the cephalostat to thereby grant more usable space around the device for revolving an x-ray source and co-axial film holder and further eliminating shadows on the radiograph, otherwise caused by protruding adjustment and support arm components of known positioners.
Cephalostats typically provide head positioning means including earposts that carry ear pins or plugs for insertion into the ear canals. Thereby the porion axis is aligned between the ear pins so that accurate measurements and permanent radiographs for cephalometric studies may be generated from patients at different periods of time during growth or orthodontia with the desirable capability of allowing the practitioner to make exact comparative diagnoses and study, and the clear advantages obtained thereby for effective treatment.
Cephalostats are useful for tomographic type of radiographic series wherein an x-ray source and film holder revolve about the patient's head in a selected series of revolutions. Additionally, cephalostats may be used in more conventional x-ray tube alignments in which the x-ray tube is fixed for a particular roentgenograph and wherein, in sequence, the patient's head may be positioned laterally, obliquely, anteriorly or posteriorly with regard to the x-ray tube and to an x-ray film holder disposed in alignment with the axis of the x-ray tube whereby front, side, back and angular radiographs may be taken so that cephalometric studies may be made and compared with subsequent or earlier radiographs for study.
For both tomographic and fixed-type x-ray tube techniques, involving lateral, posterior, anterior and oblique radiography, cephalostats have been sought which include head positioning means having earposts and earplug means that are compact, sturdy, tightly and smooth fitting with the cephalostat housing, wherein the positioning means are adjustable to move the earplugs inwardly of the ear canal, and outwardly therefrom for quick, and efficient and exact positioning of the patient's head. The positioning primarily involves locating the porion axis and Frankfort plane in standard relationships to the film for radiographic studies, particularly those involved with study of the dentition and temporal-mandibular joint (TMJ). An adjustable assembly would be desirable that would offer a compact arrangement allowing x-ray equipment and film holders, as well as other positioning means such as nasion positioner, orbitali locator, and forehead and chin positioners, to be utilized without protuberances extending outwardly of the cephalostat housing. Furthermore, eliminating such protuberances would be helpful to prevent corresponding shadows or blocked-out zones on the radiographs from occurring. Thus, particularly for tomographic techniques, a non-protruding, adjustable head positioning means would be highly desirable to increase the arc within which the x-ray tube and axially aligned film holder might move. Additionally, this would also permit a closer positioning of the x-ray tube and film holder to the patient's head as might be required, as well as allowing the carrying arm and support means for the x-ray tube and film holder to have greater spatial freedom of movement with respect to the cephalostat by the elimination of protruding adjustment arm means and the like.